The above-referenced U.S. application discloses a method and apparatus in which sodium bisulfite can be reacted substantially instantaneously with a slurry of lime by conflowing two streams of the reactants into a special mixing nozzle at rapid flow rates to create turbulance in the nozzle and thereby to effect thorough mixing of the reactants. The disclosed process provides the advantage of eliminating the need for residence times of the reactants in cascaded, stirred batch-mix reactors. Thus, the process enables the capital cost required in the regeneration phase of the Double Alkali flue gas desulfurization process to be reduced.
One of the disadvantages of the disclosed process is the need to utilize a lime slurry as a reactant for the sodium bisulfite. Because the lime reacts instantaneously with the sodium bisulfite in the nozzle, it is a highly desirable reactant. However, because of its cost, lime is undesirable as compared with other reactants, such as limestone.